Heretofore, it has been known to use building panels made from synthetic plastic materials in the manufacture of houses. One of these materials, expanded polystyrene, has proven to be a valuable insulation means for conserving energy when installed, so as to form an envelope surrounding an enclosed residential volume. Because the expanded polystyrene has a very low melting point, this material will be transformed into a vapor when exposed to temperatures above 200.degree. F., and it is necessary to cover all exposed expanded polystyrene surfaces with gypsum wallboard or sprayed plaster or concrete in order to assure that in the event of a fire, the material will withstand heat for a sufficient period of time to allow occupants to vacate the building. If the wallboard or plastered surfaces are adhered to the polystyrene, transmission of heat through these surfaces will eventually cause the expanded polystyrene to melt, and the surfacing materials will then fall away from the walls and ceiling surfaces.